Methods for user equipment measurements on additional reference symbols during idle mode for power saving

ABSTRACT

A wireless communication device having a receiving module, a transmitting module, and a processor which includes a determining module, and a processing module, wherein the wireless communication device is arranged to perform a method for power saving when operating in idle mode in a wireless communication system. Transmissions of a first set of reference symbols, RSs, and a second set of RSs are provided in the wireless communication system. The method includes estimating transmission pattern of the second set of RSs, and determining when to wake up in the idle mode to perform associated measurements based on the estimated transmission pattern of the second set of RSs. The first set of RSs are provided periodically, and the second set of RSs are provided in any of periodic, semi-persistent or aperiodic transmissions.

TECHNICAL FIELD

Embodiments herein relate to a user equipment and methods therein forpower saving. In particular, they relate to estimate transmissionpattern of additional references symbols to perform measurement duringidle mode in a wireless communication system.

BACKGROUND

A Universal Mobile Telecommunications System (UMTS) is a thirdgeneration (3G) telecommunication network, which evolved from the secondgeneration (2G) Global System for Mobile Communications (GSM).Specifications for the Evolved Packet System (EPS), also called a FourthGeneration (4G) network or Long Term Evolution (LTE), have beencompleted within the 3rd Generation Partnership Project (3GPP) and thiswork continues in the coming 3GPP releases, for example to specify aFifth Generation (5G) New Radio (NR) network.

The 3GPP is defining technical specifications for 5G NR. In release 15(Rel-15) NR, a user equipment (UE) can be configured with up to fourcarrier bandwidth parts (BWPs) in the downlink with a single downlinkcarrier bandwidth part being active at a given time. A UE can beconfigured with up to four carrier bandwidth parts in the uplink with asingle uplink carrier bandwidth part being active at a given time. If aUE is configured with a supplementary uplink, the UE can additionally beconfigured with up to four carrier bandwidth parts in the supplementaryuplink with a single supplementary uplink carrier bandwidth part beingactive at a given time.

For a carrier bandwidth part with a given numerology μ_(i), a contiguousset of physical resource blocks (PRBs) are defined and numbered from 0to N_(BWP) _(i) ^(size)−1, where i is the index of the carrier bandwidthpart. A resource block (RB) is defined as 12 consecutive subcarriers inthe frequency domain.

Multiple orthogonal frequency-division multiplexing (OFDM) numerologies,μ, are supported in NR as given by Table 1, where the subcarrierspacing, Δf, and the cyclic prefix for a carrier bandwidth part areconfigured by different higher layer parameters for downlink (DL) anduplink (UL), respectively.

TABLE 1 Supported transmission numerologies. μ Δf = 2^(μ) · 15 [kHz]Cyclic prefix 0 15 Normal 1 30 Normal 2 60 Normal, Extended 3 120 Normal4 240 Normal

Physical Channels

A downlink physical channel corresponds to a set of resource elementscarrying information originating from higher layers. The followingdownlink physical channels are defined:

-   -   Physical Downlink Shared Channel, PDSCH    -   Physical Broadcast Channel, PBCH    -   Physical Downlink Control Channel, PDCCH

PDSCH is the main physical channel used for unicast downlink datatransmission, but also for transmission of random access response (RAR),certain system information blocks, and paging information. PBCH carriesthe basic system information, required by the UE to access the network.PDCCH is used for transmitting downlink control information (DCI),mainly scheduling decisions, required for reception of PDSCH, and foruplink scheduling grants enabling transmission on PUSCH.

An uplink physical channel corresponds to a set of resource elementscarrying information originating from higher layers. The followinguplink physical channels are defined:

-   -   Physical Uplink Shared Channel(PUSCH)    -   Physical Uplink Control Channel (PUCCH)    -   Physical Random Access Channel (PRACH)

PUSCH is the uplink counterpart to the PDSCH. PUCCH is used by UEs totransmit uplink control information, including Hybrid automatic repeatrequest (HARQ) acknowledgements, channel state information reports, etc.PRACH is used for random access preamble transmission.

NR Reference Symbols

The ultra-lean design principle in NR aims to minimize the always-ontransmissions that exist in earlier systems, e.g. LTE cell-specificreference signal (CRS) reference symbols. Instead, NR provides referencesymbols such as Synchronization Signal Blocks (SSBs) on a periodicbasis, e.g. by default once every 20 ms. In addition, for connected modeUEs, typically a set of reference symbols are provided for optimal linkperformance. Some of these reference symbols are clarified below.

Channel Status Information-Reference Signal (CSI-RS) for Tracking

A UE in Radio Resource Control (RRC) connected mode is expected toreceive from the network (NW) a RRC layer UE specific configuration witha NZP-CSI-RS-ResourceSet message configured including a parametertrs-Info. For a NZP-CSI-RS-ResourceSet configured with the higher layerparameter trs-Info set to “true”, the UE shall assume the antenna portwith the same port index of the configured Non-zero power (NZP) CSI-RSresources in the NZP-CSI-RS-ResourceSet is the same.

-   -   For frequency range 1 (FR1), the UE may be configured with one        or more NZP CSI-RS set(s), where a NZP-CSI-RS-ResourceSet        consists of four periodic NZP CSI-RS resources in two        consecutive slots with two periodic NZP CSI-RS resources in each        slot. If no two consecutive slots are indicated as downlink        slots by tdd-UL-DL-ConfigurationCommon message or        tdd-UL-DL-ConfigDedicated message, then the UE may be configured        with one or more NZP CSI-RS set(s), where a        NZP-CSI-RS-ResourceSet consists of two periodic NZP CSI-RS        resources in one slot.    -   For frequency range 2 (FR2), the UE may be configured with one        or more NZP CSI-RS set(s), where a NZP-CSI-RS-ResourceSet        consists of two periodic CSI-RS resources in one slot or with a        NZP-CSI-RS-ResourceSet of four periodic NZP CSI-RS resources in        two consecutive slots with two periodic NZP CSI-RS resources in        each slot.

A UE configured with NZP-CSI-RS-ResourceSet(s) configured with higherlayer parameter trs-Info may have the CSI-RS resources configured as:

-   -   Periodic, with the CSI-RS resources in the        NZP-CSI-RS-ResourceSet configured with same periodicity,        bandwidth and subcarrier location    -   Periodic CSI-RS resource in one set and aperiodic CSI-RS        resources in a second set, with the aperiodic CSI-RS and        periodic CSI-RS resource having the same bandwidth with same RB        location and the aperiodic CSI-RS being ‘QCL-Type-A’ and        ‘QCL-Type-D’, where applicable, with the periodic CSI-RS        resources. For frequency range 2, the UE does not expect that        the scheduling offset between the last symbol of the PDCCH        carrying the triggering DCI and the first symbol of the        aperiodic CSI-RS resources is smaller than the UE reported        ThresholdSched-Offset. The UE shall expect that the periodic        CSI-RS resource set and aperiodic CSI-RS resource set are        configured with the same number of CSI-RS resources and with the        same number of CSI-RS resources in a slot. For the aperiodic        CSI-RS resource set, if triggered, and if the associated        periodic CSI-RS resource set is configured with four periodic        CSI-RS resources with two consecutive slots with two periodic        CSI-RS resources in each slot, the higher layer parameter        aperiodicTriggeringOffset indicates the triggering offset for        the first slot for the first two CSI-RS resources in the set.

A UE does not expect to be configured with a CSI-ReportConfig that islinked to a CSI-ResourceConfig containing an NZP-CSI-RS-ResourceSetconfigured with trs-Info and with the CSI-ReportConfig configured withthe higher layer parameter timeRestrictionForChannelMeasurements set to‘configured’.

A UE does not expect to be configured with a CSI-ReportConfig with thehigher layer parameter reportQuantity set to other than ‘none’ foraperiodic NZP CSI-RS resource set configured with trs-Info.

A UE does not expect to be configured with a CSI-ReportConfig forperiodic NZP CSI-RS resource set configured with trs-Info.

A UE does not expect to be configured with a NZP-CSI-RS-ResourceSetconfigured both with trs-Info and repetition.

Each CSI-RS resource, defined in Clause 7.4.1.5.3 of [4, TS 38.211], isconfigured by the higher layer parameter NZP-CSI-RS-Resource with thefollowing restrictions:

-   -   the time-domain locations of the two CSI-RS resources in a slot,        or of the four CSI-RS resources in two consecutive slots, which        are the same across two consecutive slots, as defined by higher        layer parameter CSI-RS-resourceMapping, is given by one of        -   l∈{4,8}, l∈{5,9}, or l∈{6,10 } for frequency range 1 and            frequency range 2,        -   l∈{0,4}, l∈{1,5}, l∈{2,6}, l∈{3,7}, l∈{7,11}, l∈{8,12} or            l∈{9,13} for frequency range 2.    -   a single port CSI-RS resource with density _(p)=3 given by Table        7.4.1.5.3-1 from [4, TS 38.211] and higher layer parameter        density configured by CSI-RS-ResourceMapping.    -   the bandwidth of the CSI-RS resource, as given by the higher        layer parameter freqBand configured by CSI-RS-ResourceMapping,        is the minimum of 52 and N_(BWP,i) ^(size)resource blocks, or is        equal to N_(BWP,i) ^(size)resource blocks. For operation with        shared spectrum channel access, freqBand configured by        CSI-RS-ResourceMapping, is the minimum of 48 and N_(BWP,i)        ^(size)resource blocks, or is equal to N_(BWP,i) ^(size)resource        blocks.    -   the UE is not expected to be configured with the periodicity of        2^(μ)×10 slots if the bandwidth of CSI-RS resource is larger        than 52 resource blocks.    -   the periodicity and slot offset for periodic NZP CSI-RS        resources, as given by the higher layer parameter        periodicityAndOffset configured by NZP-CSI-RS-Resource, is one        of 2^(μ)X_(p) slots where X_(p)=10, 20, 40, or 80 and where p is        defined in Clause 4.3 of [4, TS 38.211].    -   same powerControlOffset and powerControlOffsetSS given by        NZP-CSI-RS-Resource value across all resources.

NZP CSI-RS

The UE can be configured with one or more NZP CSI-RS resource setconfiguration(s) as indicated by the higher layer parametersCSI-ResourceConfig, and NZP-CSI-RS-ResourceSet. Each NZP CSI-RS resourceset consists of K≥1 NZP CSI-RS resource(s).

The parameters for which the UE shall assume non-zero transmission powerfor CSI-RS resource are configured via the higher layer parameterNZP-CSI-RS-Resource, CSI-ResourceConfig and NZP-CSI-RS-ResourceSet foreach CSI-RS resource configuration can be referred to Rel. [4, TS38.211].

All CSI-RS resources within one set are configured with same density andsame number of CSI-RS ports, except for the NZP CSI-RS resources usedfor interference measurement.

The UE expects that all the CSI-RS resources of a resource set areconfigured with the same starting RB and number of RBs and the same codedivision multiplexing (CDM) values and pattern.

The bandwidth and initial common resource block (CRB) index of a CSI-RSresource within a BWP, as defined in Clause 7.4.1.5 of [4, TS 38.211],are determined based on the higher layer parameters nrofRBs andstartingRB, respectively, within the CSI-FrequencyOccupation IEconfigured by the higher layer parameter freqBand within theCSI-RS-ResourceMapping IE. Both nrofRBs and startingRB are configured asinteger multiples of 4 RBs, and the reference point for startingRB isCRB 0 on the common resource block grid. If startingRB<N_(BWP) ^(start),the UE shall assume that the initial CRB index of the CSI-RS resource isN_(initialRB)=otherwise N_(initialRB)=startingRB. If nrofRBs>N_(BWP)^(size)+N_(BWP) ^(start)−N_(initialRB), the UE shall assume that thebandwidth of the CSI-RS resource is N_(CSI-RS) ^(BW)=22 N_(BWP)^(size)+N_(BWP) ^(start)−N_(initialRB), otherwise N_(CSI-RS)^(BW)=nrofRBs. In all cases, the UE shall expect that N_(CSI-RS)^(BW)≥min (24, N_(BWP) ^(size)).

The following are short explanations for some IE parameters, fordetailed information, see TS 38.214.

The IE NZP-CSI-RS-Resource is used to configure Non-Zero-Power (NZP)CSI-RS transmitted in the cell where the IE is included, which the UEmay be configured to measure on.

The IE NZP-CSI-RS-ResourceId is used to identify oneNZP-CSI-RS-Resource.

The IE NZP-CSI-RS-ResourceSet is a set of Non-Zero-Power (NZP) CSI-RSresources (their IDs) and set-specific parameters.

The IE NZP-CSI-RS-ResourceSetId is used to identify oneNZP-CSI-RS-Resource Set.

The IE CSI-ResourceConfig defines a group of one or moreNZP-CSI-RS-ResourceSet, CSI-IM-Resource Set and/or CSI-SSB-Resource Set.

The IE CSI-ResourceConfigId is used to identify a CSI-ResourceConfig.

The IE CSI-ResourcePeriodicityAndOffset is used to configure aperiodicity and a corresponding offset for periodic and semi-persistentCSI resources, and for periodic and semi-persistent reporting on PUCCH.Both the periodicity and the offset are given in number of slots. Theperiodicity value slots4 corresponds to 4 slots, slots5 corresponds to 5slots, and so on.

The IE CSI-RS-ResourceConfigMobility is used to configure CSI-RS basedRRM measurements.

The IE CSI-RS-ResourceMapping is used to configure the resource elementmapping of a CSI-RS resource in time- and frequency domain.

In NR, connected mode, a UE is provided either with periodic,semi-periodic or aperiodic CSI-RS/TRS, i.e. Tracking reference signalsor CSI RS for tracking, so it can measure the channel qualities, and/ortrack the reference signal in order to fine tune its time and frequencysynchronization. This mechanism is only specified for the RRC_Connectedmode. The UE needs to rely on SSB measurements during RRC_Idle orInactive mode for e.g. Automatic Gain Control (AGC) and sync purposesand for other functions. The default operation is that the UE wakes upat least two SSBs before a Paging Occasion (PO), and at the first one itperforms AGC, and at the second performs Automatic Frequency Control(AFC) and timing synch before monitoring the PO.

The problem with relying on SSBs is that SSBs have relatively long timeintervals, e.g. 20 ms, and sometimes the UE may need to stay away fromdeep sleep for a long total time before it is able to e.g. read itspaging message after previous available SSB receptions, which in turnleads to a waste of UE power.

SUMMARY

There is thus a need for methods with which the UE can save power inidle mode.

As discussed above, besides SSBs there are other additional RSs ornon-SSB RSs, e.g. CSI-RS/TRS and the UE is not aware of the potentialexistence of such RSs during RRC_Idle or Inactive mode. If the UE cancontinue exploiting potential CSI-RS/TRS or other non-SSB RSs duringidle or inactive mode to perform required idle mode tasks, reduce thenumber of SSB instances to receive, between, then it can remain in deepsleep longer and thereby achieve higher power savings.

According to an aspect of embodiments herein, the object is achieved bya method performed in a UE for power savings in idle mode in a wirelesscommunication system. Transmissions of a first set of reference symbols(RSs), e.g. SSBs, and a second set of RSs, i.e. non-SSB RSs, e.g.CSI-RS/TRS, are provided in the wireless communication system. The UEestimates transmission pattern of the second set of RSs and determineswhen to wake up in the idle mode to perform associated measurementsbased on the estimated transmission pattern of the second set of RSs.

The UE may gain knowledge regarding the second set of RSs, i.e. non-SSBRSs, during RRC_Idle or Inactive mode either through learning, or beinginformed directly from the NW node. When the UE have this knowledge,embodiments herein provide how the additional RSs can be exploited,particularly for power savings.

Embodiments herein provide methods and mechanisms with which the UEfirst learns that the network node keeps transmitting non-SSB RS, e.g.,CSI-RS/TRS, even while the UE is in RRC_Idle or Inactive mode, andsecond it learns pattern of potential additional RSs, besides the SSBs,during RRC_Idle or Inactive mode. Finally, based on which of the RSs iscloser to the PO, the UE decide to wake up and perform the associatedmeasurements.

Embodiments herein also provide several methods and mechanisms withwhich the UE may exploit the presence of non-SSB RSs to obtain powersavings. Methods are defined as:

Determining whether the available non-SSB RS may be advantageously used,e.g. by either considering the temporal order of occurrence of relevantSSB, TRS, and/or PO position, or by comparing the total energyconsumption of the baseline and alternative, i.e. non-SSB RS-aided,action sequences. The baseline is UE just using SSBs for AGC and AFCwith no aid from non-SSB RSs. The alternatives are UE performing AGC andAFC with aid from non-SSB RSs besides SSBs where SSBs and non-SSBs mayhave different temporal sequences.

Determining which RS combination, e.g. SSB, non-SSB or a combination ofboth, may be used for the required idle mode tasks.

The proposed solution provide UE with mechanisms to learn theconfiguration of additional RSs while in RRC Connected state, becomeaware of the presence and pattern of potential additional RSs, besidesthe SSBs, during RRC_Idle or Inactive mode, and then use this knowledgein order to achieve a higher power savings by enabling longer deep sleepphases.

The proposed solutions also provide UE with mechanisms to exploit theknowledge of non-SSB RSs during RRC_Idle or Inactive mode to performrequired idle mode tasks to achieve lower power consumption.

Therefore, embodiments herein provide a method for UE for power savingby estimating and exploiting additional RSs provided in the wirelesscommunication system.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of embodiments herein are described in more detail withreference to attached drawings in which:

FIG. 1 illustrating a wireless communication system in which embodimentsherein may be implemented in;

FIG. 2 is a flow chart illustrating a method performed in a UE accordingembodiment herein;

FIG. 3 illustrating one example scenario of reference symbols positions;

FIG. 4 illustrating another example scenario of reference symbolspositions;

FIG. 5 illustrating another example scenario of reference symbolspositions;

FIG. 6 illustrating another example scenario of reference symbolspositions;

FIG. 7 illustrating another example scenario of reference symbolspositions;

FIG. 8 illustrating another example scenario of reference symbolspositions; and

FIG. 9 is a schematic block diagram illustrating one embodiment of a UE.

DETAILED DESCRIPTION

FIG. 1 is a schematic overview depicting a wireless communication system100 in which embodiments herein may be implemented. The wirelesscommunication system 100 may comprise any wireless system or cellularnetwork, such as a Long Term Evolution (LTE) network, any 3^(rd)Generation Partnership Project (3GPP) cellular network, a FourthGeneration (4G) network, a Fifth Generation (5G) or NR network etc.

In the wireless communication system 100, wireless communication devicese.g. a user equipment 130 such as a mobile station or terminal, awireless terminal communicate via one or more Radio Access Technologye.g. RAT 1, RAT2 to one or more core networks (CN). It should beunderstood by the skilled in the art that “wireless communicationdevice” is a non-limiting term which means any terminal, wirelesscommunication terminal, user equipment, Machine Type Communication (MTC)device, IoT device, Device to Device (D2D) terminal, or node e.g. smartphone, laptop, mobile phone, sensor, relay, mobile tablets or even asmall base station communicating within a cell. The terms “userequipment”, “UE” and “wireless communication device” are usedinterchangeable herein.

Network nodes operate in the wireless communication networks such as afirst network node 110 and a second network node 120. The first networknode 110 provides radio coverage over a geographical area, a cell areaor a service area 111, which may also be referred to as a beam or a beamgroup where the group of beams is covering the service area of a firstradio access technology RAT 1, such as 5G, LTE, LTE-M, Wi-Fi or similar.The second network node 120 provides radio coverage over a geographicalarea, a service area 121, which may also be referred to as a beam or abeam group where the group of beams is covering the service area of asecond radio access technology RAT 2, such as 5G, LTE, LTE-M, Wi-Fi orsimilar. The service areas 611 and 621 for e.g. LTE and NR, may overlapat some area. The first and second network nodes 110, 120 may berefereed as eNB, gNB etc.

In RRC_Connected state, a UE 130 is typically configured with a set ofadditional, in addition to SSB, non-SSB reference symbols (RSs) used foroptimal link operations e.g., TRS or CSI-RS. The term non-SSB RS heremay refer to CSI-RS or TRS, but other RS types may also be relevant.Such usage refers to the provision including configuration of the RSs bythe gNB, the measurements and/or receiver tuning carried out by the UEon those RSs, and conditionally, based on a separate gNB-providedconfiguration, the reporting of the measurement carried out by the UE tothe gNB leading to a mutual understanding of the link quality.Nevertheless, the NW node may choose to not turn off the non-SSB RS, ifa UE transitions to RRC_Idle/Inactive. For the context of thisapplication, from the UE viewpoint, the presence information regardingthe non-SSB RSs are either explicitly provided by the NW node and thusguaranteed in specific time/frequency (T/F) resources, or it has to bedetected or learned by the UE itself, and thus the latter becomesassociated with a probability.

There are two alternatives for UE to detect or learn the presenceinformation regarding non-SSB RSs.

Alternative 1: UE learning gNB behavior with regard to non-SSB RSsduring RRC_Connected

During RRC_Connected, the NW node may provide non-SSB RSs to the UE inperiodic, semi-persistent, or aperiodic manner. In all cases, the NWnode then provides information about characteristics of the RSs such asscrambling code, comb/interleaving and symbol patterns, Quasi-Colocation(QCL) information e.g. relation to other beams, antenna portsconfiguration, power offsets, etc. For the UE to know where and when inthe time/frequency (T/F) resources the RSs occur, the UE also obtainsthe provision schedule for periodic and semi-persistent RSs during itsconnected mode operation.

In case of aperiodic RSs, the RSs may be provided in any T/F resourcesaccording to instantaneous NW node preferences upon which the UE isnotified in a Downlink Control Information (DCI) imminent to provision,and thus in a general case, the provision schedule is not known to theUE in advance. This approach gives the NW node the flexibility to adaptthe provision based on specific needs exemplified further below.

In one embodiment, the UE learns that even though the NW node has chosento take an aperiodic configuration approach for some RSs, the NW node isstill following a specific pattern when providing RSs. That is the RSsassociated with a NW-ordered CSI report request arrive in periodicmanner.

In a related embodiment, the UE learns that the aperiodic RSstriggering, e.g. CSI-RS trigger occurs in periodic manner with aspecific period or other T/F parameters. For example, the NW nodetriggers the UE every 80 ms to report L1_RSRP, or every 40 ms for CSI-RSreport. It may also learn that the frequency location is unchanged orchanges according to a consistent pattern. For example, the CSI-RS isaperiodic, however, it comes periodically within a T/F window.

In yet another embodiment, the UE learns that the provision schedule andRS characteristics for a certain RS is connected to a UE behavior. Forexample, the UE may detect that RSs are provided and reports arerequested by the NW node often, e.g. every 40th ms, with a dense RSconfiguration, e.g. number of symbols, interleaving pattern etc., andwhen the UE is moving at a high speed, e.g. above certain threshold,whereas less often e.g. every 80th ms, with a sparse configurationotherwise.

In another embodiment, the UE learns the specific NW node behavior withregard to RSs in a specific cell, a specific beam, BWP, FR ranges, andso on. For example, the NW node may behave the same or different, indifferent cells, beams, group of beams e.g. connected to a wide beam,BWP or FR range. For example, in FR1, the RSs may be less frequent thanFR2 or the other way around. Or, in one cell, the RSs may come in thesame T/F as the other cell, or a shifted version, or according tocompletely different pattern. The UE may then separately learn thepatterns for the different frequency ranges. The UE will then store suchinformation about the configuration schedule (T/F) and RS parameterconfiguration for the different cells/BWPs etc. The UE may also observethat RS configuration parameters, even though seemingly different, maybe following a specific pattern, e.g. that the scrambling seedconfiguration used for the RSs in different cells are based on the cellidentity.

Alternative 2: UE learning if non-SSB RSs are available duringRRC_Idle/Inactive

The objective with this aspect is that even though the aforementionedconfigurations of Alternative 1 are specifically provided for a UE inRRC_Connected mode, it is beneficial for UEs in RRC_Idle/Inactive modeto employ or enjoy the presence of these RSs as they might anyways betransmitted by the NW node.

In one embodiment, the UE may learn if periodic or semi-persistentnon-SSB RSs are present during the time when the UE is inRRC_Idle/Inactive. For brevity, the terminology RRC_Idle/Inactive isabbreviated to “idle” from now on. For example, the UE may wake-up inidle at the time that the RSs are assumed to be present, to check ifthey are present or not. To do so, the UE may apply different detectiontechniques. For example, the UE may correlate the received signal withthe expected RS pattern in time or frequency domain to verify if itcontains a RS or no signal. For example, if the correlation result isabove a specific threshold, the UE may note that this is a RS, but ifnot, then the UE assumes there is no RS signal present during idle time.

In one embodiment of the present invention, the UE may correlate withseveral assumed sequences e.g. comb/interleaving patterns, symboldensity, etc. The UE may further utilize the learnings outlined inAlternative 1 for the most probable RS reference sequence correlation.The UE may e.g. based on its UE speed, or based on specific knowledgesuch as detected access points of any technology such as WiFi, assumethat it is on a high-speed train probably together with other connectedUEs in high-speed mode being provided with RSs and correlate with asequence typically configured for such situation. Furthermore, the UEmay utilize the information and assume periodicity of RS based on theinformation. Such information need not only be speed-based, but alsotime and/or location based. For example, in earlier aspects the UE mighthave learned that in heavy traffic areas, RSs are provided with a higherperiodicity.

For the detector itself, the UE may further not wake up the wholereceiver, but use a lower power receiver to wake-up at the expectednon-SSB RSs arrival times to detect the presence or absence of theassociated RSs. Furthermore, the UE may use previous SSB or non-SSB RSmeasurements for calibrating the detector.

The UE may further decide to perform this procedure one or more timeduring idle time, or perform the same in different cells, BWPs, beams,or FR ranges. For example, the UE may note that the non-SSB RSs, e.g.TRSs are present during idle time in one cell but not in another one, orthey are present in FR2 but not in FR1, or vice versa, and so on.

According to some embodiments herein, the UE may perform this proceduremore often in specific cells and/or during certain times of day. Forexample, it might be so that the NW node only provides such RSs onlywhen there are UEs in RRC_Connected state and not otherwise. Therefore,the UE in idle state, may learn that during certain occasions e.g. busyhours, or cells e.g. busy locations, there is a higher probability thatRSs are provided compared to other circumstances.

In another embodiment, the UE may apply the procedure described fordetection of non-SSB RSs during idle time for periodic orsemi-persistent RSs to aperiodic RSs as learned in Aspect 1. Forexample, the UE may wake-up during idle time, either the main receiveror a low power receiver with a low power detector, in T/F componentswhere the UE would expect that the aperiodic RS arrives following thepattern learned in Aspect 1.

Furthermore, as in the case of periodic or semi-persistent RSs, the UEmay learn whether the non-SSB RSs during idle time for aperiodic RSsremain present in a specific cell, BWP, beam, FR range and so on evenwhen the given UE has left the connected mode. For example, theaperiodic RSs may be present during idle time for FR2 but not for FR1 orvice versa, or for both, or they may be present in one cell but not inanother one, or they are present in all the cells, and so on.

In the examples above, the UE may further learn which of the specificRSs are present during idle time. For example, the UE may learn that TRSis present, but CSI-RS in general is not present, or that all of themare present, or a subset of them.

In an extension of Alternative 2, the UE may test for the presence ofnon-SSB RS in idle mode even when it has not obtained or learned RSconfiguration info in connected mode in the given cell. This approachmay be used if the UE is mobile and changes its camping cell so that thecurrent camping cell is no longer the last connected-mode cell for theUE. In such case, the UE utilizes its gained knowledge of Alternative 1e.g. with respect to scrambling sequences assumed to be used for the newcell in case the scrambling sequence was based on cell identity. In oneembodiment, the UE may attempt detecting the presence of RS in T/Flocations and transmission patterns and/or according to scrambling andother resource set parameters or parameter combinations that were validin its previous serving cells. If the previous serving cells hadmultiple different RS configurations, the UE may attempt detectionaccording to multiple or all previously encountered patterns. In anotherembodiment, the UE may use the code info from previous serving cells butattempt detection in a wider range of T/F resource sets, e.g. in a givensymbol number of multiple or all slots. The UE may perform energydetection to identify symbols where the RS are likely transmitted andattempt correlation detection in symbols whose energy level or detectedenergy pattern matches the expected RS energy or pattern.

A method performed in a UE 130 according to embodiments herein for powersavings in a wireless communication system 100 will be described withreference to FIG. 2 . Transmissions of a first set of reference symbols(RSs) such as SSBs, and a second set of RSs, such as TRS, CSI-RS etc.non-SSB RS are provided in the wireless communication system 100. Themethod comprises the following actions:

Action 210

The UE 130 estimates transmission pattern of the second set of RSs;

Action 220

The UE 130 determines when to wake up in the idle mode to performassociated measurements based on the estimated transmission pattern ofthe second set of RSs.

The associated measurements may be AGC, AFC, timing drift correctionetc.

According to embodiments herein, a distinguishing is made between theabove mentioned two aspects, i.e. the presence information regarding thenon-SSB RSs are either explicitly provided by the NW node and thusguaranteed in specific time/frequency (T/F) resources, or it has to bedetected or learned by the UE itself. Mechanisms with which the UE maybe able to exploit the non-SSB RSs during RRC_Idle/Inactive mode forpower saving under each aspect are provided.

In the remaining text, the terms NW, network node, base station and gNBare used interchangeably. Furthermore, when referring to UE being inidle mode, it means the UE is in RRC_Idle or Inactive state.Additionally, for the sake of simplicity the example embodiments focuson Tracking reference signals (TRS) as a specific non-SSB RS.Nevertheless, the same concept and mechanisms can be readily extended toother non-SSB RSs, e.g., CSI-RS.

In the following, example embodiments of UE exploiting the presence ofnon-SSB RSs for power savings are described.

In one embodiment, the UE after confirmation that the non-SSB RSs, or asubset of them, e.g., TRS is present during idle time, the UE mayexploit this information to optimize its different procedures, e.g.,AGC, T/F synchronization and so on. Particularly, the UE may use thisinformation to achieve power savings.

In one example, the UE may note that the non-SSB RS, e.g. TRS is closerto a PO than SSB, and thus it may decide to skip the SSB measurement,and directly wake-up and measure the TRS before PO, e.g. for thepurposes of coarse T/F synchronization. As such the UE may deep-sleepfor a longer time and thus achieve a higher power saving.

In another example, the UE may note that there is a TRS closer to a SSBthan another SSB, let's say TRS is between SSB1 and SSB2, with SSB2being the closest SSB to PO, and thus instead of waking up for SSB1 forAGC, the UE may skip SSB1, and wake-up for TRS for AGC before SSB2 formeasurement. Again, the UE may sleep longer and thus achieve a higherpower savings, or consume lower energy. In a related example, the TRSoccasion may be after SSB2, and in this case the UE may decide to skipSSB1 for AGC based on the probability of TRS being present after SSB1.For example, if the probability is high or higher than a threshold, theUE skips SSB1 for AGC, perform AGC on SSB2, and AFC on TRS, and in theworst case if TRS is not present, in the next PO, it only relies on SSB.Nevertheless, if the probability is not high enough e.g. lower than athreshold, then the UE may only rely on SSB.

In another embodiment, and particularly when the non-SSB RS consist ofmultiple slots, e.g. TRS with two consecutive slots, the UE may decideto perform both AGC and AFC on the same TRS if there is sufficient timebetween the slots for reliable AGC/AFC, and then skip all the SSBs. Hereagain, for the sake of robustness, the UE may decide to choose the TRSbefore or after the latest SSB before PO based on the probability of TRSbeing present.

In another embodiment, the UE may decide to use the detection result inAlternative 2 directly. That is if the detection result shows that in aspecific T/F component, a non-SSB RS is present, then the UE may decideto perform a measurement on this RS directly, and skip the immediate SSBmeasurement. In a related realization, the UE may first use a low-powerdetector to detect the non-SSB RS, and then use the full receiver ifneeded for additional operations, e.g. synchronization and so on.

Depending how the UE obtains the information on the transmission of thesecond set of RSs, the method performed in a UE 130 according toembodiments herein for power savings are described in the following twoaspects.

Aspect 1: UE exploitation of guaranteed non-SSB RS during idle mode forpower saving.

According to some embodiments, the UE receives the information on thetransmission of the second set of RSs from a network node. Herein, it isassumed that the UE has been provided by the NW node with theinformation regarding the resources within which the second set of RSs,e.g. TRS, is present during idle mode and explicit or implicitinformation that the second set of RSs, e.g. TRS, will be availableduring some time interval forward. The configuration information mayinclude the T/F locations, Resource Element (RE) pattern in thesymbol(s), period, code sequence, associated Transmission ConfigurationIndication (TCI) state, etc. in general all parameters required fordetecting, measuring, or otherwise utilizing the second set of RSs, e.g.TRS, signal by the UE. As such the UE has an accurate knowledge aboutthe presence of the second set of RSs, e.g. TRS, in idle mode.

In one class of embodiments, the UE may determine whether and how toutilize the second set of RSs, e.g. TRS, based on the temporal order ofoccurrence of the first and second set of RSs, and/or Paging Occasion,PO, positions, e.g. the temporal order of occurrence of SSB, TRS, andpaging PDCCH signals in the vicinity of a PO.

According to some embodiments, the UE may determine sleeping mode basedon the temporal order of occurrence of the first and second set of RSs.

In one embodiment, the TRS is located between two SSBs, namely SSBoccasion x, called SSB_x hereafter, and SSB occasion x+1, called SSB_x+1hereafter, as shown in FIG. 3 , with SSB_x+1 being the one closest to aUE's paging occasion (PO). As such the UE may decide to exploit TRS forAGC and SSB_x+1 for AFC, thereby skipping

SSB_x, and staying in a radio deep sleep state for a longer time beforewaking up for TRS measurements. Furthermore, depending on the amount ofavailable time between TRS and SSB_x+1, or SSB_x+1 and PO, the UE maydecide to choose the appropriate sleeping mode, e.g., a light or a microsleep. Note that paging is just one example. PO may be any type of UEactivity that requires the UE to have proper reception level, i.e. AGCis needed, and synchronization towards the network node with regardingto frequency and timing, i.e. AFC is needed. Other examples may bebroadcast or multi-cast Channel reception, PRACH transmission etc.

In another embodiment, as depicted in FIG. 4 , out of availablereference symbols, TRS may be the closest to PO. As such, the UE mayagain skip SSB_x, but wake up for SSB_x+1 to perform AGC, and then usingTRS for AFC. Again in this case, the UE may deep sleep for a longer timeby skipping SSB_x , and then based on the available time between SSB_x+1and TRS, and TRS and PO, choose an appropriate power saving mode.

In another embodiment, as depicted in FIG. 5 , the UE may have an orderof occurrences as SSB_x, TRS_x, SSB_x+1, TRS_x+1, PO. In this case, ifthe distance between SSB_x+1 and TRS_x+1 is sufficiently distanced toenable a consecutive AGC, AFC, in addition to SSB_x, the UE may alsoskip TRS_x, and thus stay longer in deep sleep, before waking up forSSB_x+1 and TRS_x+1 measurements or processing.

In another embodiment, as depicted in FIG. 6 , the order of occurrencesmay be SSB_x, SSB_x+1, TRS_x, TRS_x+1, and thus the UE can skip bothSSB_x and SSB_x+1, if temporally TRS_x and TRS_x+1 are sufficientlydistanced from each other for AGC/AFC operation.

In another embodiment, if the TRS consist of two slots, and the slotduration is sufficiently large for a reliable AGC, AFC operation, the UEmay skip all other SSB and TRSs and use the same TRS for both AGC andAFC respectively associated each with one slot. In this case, theclosest TRS to PO can be used to let the UE deep sleeping for a longertime. This is depicted in FIG. 7 .

In another embodiment, as one TRS slot contains 2 TRS symbols with afixed inter symbol distance of 4, UE can exploit the 1st symbol for AGCand the 2nd symbol for AFC. Therefore, in FIG. 3 and FIG. 4 , the SSBreception can be skipped.

In another embodiment, in FIG. 3 and FIG. 4 , UE can perform AGC andcoarse time/frequency synchronization by receiving SSB, while performfiner time/frequency correction by using TRS.

In general, the signal or signal component used for AGC tuning may alsobe used for link quality estimation, e.g. serving cell Reference signalreceived power (RSRP) or Signal to Interference and Noise Ratio (SINR).The measurement result may be determined as a scaled output of acorrelator determined as magnitude of inner product of the received REcontents and a reference sequence based on the TRS or SSS contents. Inembodiments where the TRS is used for measurement purposes, theTRS-based measurement result must be made consistent with theconventional SSB-based, e.g. Secondary Synchronization Signal(SSS)-based, measurements for comparing with other-cell SSB qualityvalues; raw measurements are generally not consistent since the TRS andSSS have a different number of REs and may have different power boostingapplied by the gNB. The UE may employ one of the following approaches toachieve appropriate scaling:

-   -   Perform measurements with regarding to its serving cell based on        the SSB, e.g. SSS, and on the TRS and determine a scaling factor        as the ratio of the two. One measurement or an average of        multiple measurements with both signals during the same time        interval may be used to determine the ratio. The TRS-based power        estimate is then scaled by multiplying it by the scaling factor.    -   Estimate the relative power values of TRS REs and SSS REs during        one or more measurements and determine the number of REs used        for estimating the power of the two signals. The TRS-based power        estimate is then scaled by multiplying it by the ratio of “the        number of SSB REs times the SSB RE power” and “the number of TRS        REs times the TRS RE power”.

The UE then uses the scaled power estimate for comparison withother-cell link quality estimates.

According to some embodiments herein, the UE may determine RSutilization sequences for idle mode tasks by comparing the total energyconsumption of the utilization sequences of the first and second sets ofRSs.

The previously presented examples of TRS utilization primarily considerthe temporal order of the available signals. In a more genericembodiment, the UE also uses the detailed inter-signal distanceinformation to predict sleep opportunities, including selection of bestavailable sleep mode and accounting for the transition intervals betweensleep- and non-sleep states. The UE may determine whether the availablenon-SSB RS may be advantageously used by comparing the total energyconsumption of the baseline and alternative, e.g. non-SSB RS-aided,action sequences. The total energy estimate may include all estimatedsleep, transition, and activity phases of a given candidate RSutilization sequence. Multiple candidate sequences may be analyzed andthe sequence with least total energy metric may be selected. Forexample, as shown in FIG. 8 , SSB_x and TRS might be so close to eachother, and yet close enough to the PO so that AGC/AFC estimates on thetwo can be assumed valid at PO, so that it is more beneficial to performAGC/AFC on SSB_X/TRS rather than on the closest RSs, i.e. TRS, SSB_X+1,to the PO. Reason for this is that the UE may enjoy a longer total sleeptime before the PO.

In an extension of the above embodiment, the UE further considers thecurrent operating parameters when considering candidate sequences for RSutilization, including e.g.

-   -   validity of available AGC estimate from previous wake-up,        depending on e.g. the time since the last AGC update, previously        estimated variability of the RSSI metric over time in the        network, etc. If time passed or the variability exceeds        predetermined threshold values, a new AGC estimate must be        accommodated by a candidate sequence.    -   validity of current AFC and/or timing estimate, depending on        e.g. the time since the last AFC update, if time passed exceeds        a predetermined threshold value, a new AFC and/or timing        reference estimate must be accommodated by a candidate sequence.    -   signal quality of the available RS, at higher SINR, a smaller        number of REs are required for reliable AFC and/or measurement        operations.

Aspect 2: UE exploitation of probable non-SSB RS during idle mode forpower saving

According to some embodiments, the UE detects the transmission patternof the second set of RSs by learning mechanism. In this case the UE isaware of TRS presence during idle mode with a certain probability butnot guaranteed. For example, the UE has used some learning mechanism tolearn the pattern within which the TRS are transmitted, and then detectsthat the same patterns are repeated in Idle/Inactive modes. As in thecase of any detection, and/or learning mechanism such an awareness isassociated with a non-zero probability of erroneous estimation.Alternatively, the UE may have detected the TRS during a current orpreceding TRS occasion in idle/inactive but has no information orguarantees that the TRS will continue to be available for a certain timeinterval forward.

According to some embodiments, the UE may test for the presence ofnon-SSB RS in idle mode even when it has not obtained or learned RSconfiguration info in connected mode in the given cell, e.g. blinddetection. This approach may be used if the UE is mobile and changes itscamping cell so that the current camping cell is no longer the lastconnected-mode cell for the UE. In such case, the UE utilizes its gainedknowledge for example as of Aspect 1, e.g. with respect to scramblingsequences assumed to be used for the new cell in case the scramblingsequence was based on cell identity. In one embodiment, the UE mayattempt detecting the presence of RS in T/F locations and transmissionpatterns and/or according to scrambling and other resource setparameters or parameter combinations that were valid in its previousserving cells. If the previous serving cells had multiple different RSconfigurations, the UE may attempt to perform detection according tomultiple or all previously encountered patterns. In another embodiment,the UE may use the code info from previous serving cells but attemptdetection in a wider range of T/F resource sets, e.g. in a given symbolnumber of multiple or all slots. The UE may perform energy detection toidentify symbols where the RS are likely transmitted and attemptcorrelation detection in symbols whose energy level or detected energypattern matches the expected RS energy or pattern.

According to some embodiments, the UE determines which RS to use foridle mode tasks is based on the available probability of the second setof RSs and paging occasion pattern.

In one embodiment, if the probability of TRS presence according to thelearned pattern is high, the UE may consider this as guaranteed andemploy mechanisms similar to the ones described in Aspect 1. Possiblerare occurrences of erroneous estimation are handled as failed pagingreception and conventional recovery approaches are used in the NW.Furthermore, for robustness issues, the UE may employ TRS detection inevery occasion, or in every other one and so on, to make sure themeasured signal is actually TRS. In this case, in one approach, the UEmay employ a joint detection and estimation mechanism, to jointly detectTRS, and then apply AGC/AFC. In another approach, and particularly wheneach TRS spans more than one slot, the UE may use the first slot todetect the TRS, potentially with a lower power radio, and then applyAGC/AFC if the TRS detected. In case a TRS not detected, and there is noother RS to employ for AGC/AFC operation, then the UE may skip one PO.As such, when deciding about the probability of TRS being present, inone approach, the UE may make sure to choose the probability such thatthe specified maximum probability of missing a PO is not exceeded. Forexample, the UE might learn the paging policy/pattern of the NW andobserve that the NW pages a UE at least say three times before givingup. Hence, the UE might take a larger risk initially and base itsAGC/AFC tuning on potential TRSs before a PO or couple of POs in thisexample. However, once the UE detects missing TRS, it may adapt its riskassessment and not perform AGC/AFC tuning on potential TRS. But after asuccessful paging procedure, or alternately after immediate connectionrelease to idle/inactive, since the UE knows that it has not missed anypaging since last connection, again the UE may start taking a largerrisk and based AGC/AFC on potentially present TRSs.

In another embodiment, if the probability of TRS presence is low, orlower than a specific threshold, e.g., the probability which was set inthe previous embodiment, the UE may choose to only employ TRS occasionsbefore SSB for power savings purposes in order to have an opportunity touse the SSB should the TRS not be present. For example, if the order ofRSs, is as depicted in FIG. 3 , SSB_x, SSB_x+1, TRS, PO, the UE may justrely on the SSBs for AGC/AFC operation and ignore TRS, since if itrelies on TRS, e.g., for AFC, and then there is no TRS, it may notreliably decode PO.

Alternatively, the UE may still employ this TRS for power savingpurposes, but if not detected, employ a more powerful receiver for POmonitoring to make sure not missing the paging message.

In another example, as depicted in FIG. 4 , if the order of appearanceis SSB_X, TRS_x, SSB_x+1, TRS_x+1, PO, the UE may use SSB_x for AGC, andthen TRS_x for AFC and skip SSB_x+1/TRS_x+1, and in case TRS_x is notdetected, the UE may use SSB_x+1 as a fallback for AFC. In other words,the UE might take the risk of utilizing those TRSs that allow forbackup/fallback to available SSBs before the PO in case the TRS was notpresent. In another example, the order of appearance may be TRS, SSB_x,SSB_x+1, and PO. In this case, if TRS occasion spans at least two slots,and further the AGC/AFC validity remains in place until PO, the UE mayuse two slots of TRS for AGC/AFC, and skip both SSBs, and if TRS is notdetected, then the UE may use the default operation on the two SSBs.

To perform the method in the UE 130, the UE 130 comprises modules asshown in FIG. 9 . The UE 130 comprises a receiving module 910, atransmitting module 920, a determining module 930, a processing module940, a memory 950 etc. The determining module 930 and processing module940 may be combined as one module, shown as processor 960.

The method according to embodiments herein may be implemented throughone or more processors, such as the processor 960 in the UE 130 togetherwith computer program code for performing the functions and actions ofthe embodiments herein. The program code mentioned above may also beprovided as a computer program product, for instance in the form of adata carrier 980 carrying computer program code 970, as shown in FIG. 9, for performing the embodiments herein when being loaded into the UE130. One such carrier may be in the form of a CD ROM disc. It is howeverfeasible with other data carriers such as a memory stick. The computerprogram code may furthermore be provided as pure program code on aserver or a cloud and downloaded to the UE 130. The memory 950 in the UE130 may comprise one or more memory units and may be arranged to be usedto store received information, measurements, data, configurations andapplications to perform the method herein when being executed in the UE130.

Some example Embodiments numbered 1-17 are described below.

-   Embodiment 1: A method performed in a UE for power saving in idle    mode in a wireless communication system, wherein transmissions of a    first set of reference symbols, RSs, and a second set of RSs are    provided in the wireless communication system, the method    comprising:    -   estimating transmission pattern of the second set of RSs;    -   determining when to wake up in the idle mode to perform        associated measurements based on the estimated transmission        pattern of the second set of RSs.-   Embodiment 2: The method according to Embodiment 1, further    comprises receiving information on provision schedule for the second    set of RSs during connected mode from a network node, and wherein    estimating transmission pattern of the second set of RSs is based on    the received information.-   Embodiment 3: The method according to Embodiment 2, wherein    estimating transmission pattern of the second set of RSs comprises    detecting if the second set of RSs are present during idle mode.-   Embodiment 4: The method according to Embodiment 3, wherein    detecting if the second set of RSs are present during idle mode    comprises waking up a lower power receiver at an expected arrival    time of the second set of RSs to detect the presence or absence of    the second set of RSs.-   Embodiment 5: The method according to Embodiments 3-4, wherein    detecting if the second set of RSs are present during idle mode    comprises correlating a received signal sample sequence with a    reference sequence corresponding to an RS in the second set of RSs    in time or frequency domain to verify if a RS is present or not.-   Embodiment 6: The method according to Embodiments 3-4, wherein    detecting if the second set of RSs are present during idle mode    comprises correlating with several assumed RS sequences modified    based on any one of time offset, frequency offset or vehicular    speed.

Embodiment 7: The method according to Embodiments 3-6, wherein detectingif the second set of RSs is present during idle mode is performed one ormore times in different cells, BWPs, beams, or FR ranges based on timeand/or location.

-   Embodiment 8: The method according to Embodiments 3-6, wherein    detecting if the second set of RSs is present during idle mode is    based on the second set of RSs configuration parameters in its    previous serving cells.-   Embodiment 9: The method according to Embodiments 3-8, wherein    detecting if the second set of RSs is present during idle mode is    based on energy detection to identify symbols where the second set    of RSs are likely transmitted.-   Embodiment 10: The method according to Embodiments 3-9, wherein    detecting if the second set of RSs is present during idle mode is    based on correlating energy detections in symbols to decide if    detected energy level or detected energy pattern matches an expected    RS energy or pattern.-   Embodiment 11: The method according to any one of Embodiments 1-10,    wherein determining when to wake up to perform associated    measurements comprises optimizing AGC, AFC, time and/or frequency    synchronization procedures for power savings based on the    transmission pattern of the second set of RSs.-   Embodiment 12: The method according to any one of Embodiments 1-11,    wherein determining when to wake up to perform associated    measurements comprises optimizing sleeping mode based on the    temporal order of occurrence of the first and second set of RSs.-   Embodiment 13: The method according to any one of Embodiments 1-11,    wherein determining when to wake up to perform associated    measurements comprises determining which RS to use for idle mode    tasks based on the temporal order of occurrence of the first and    second set of RSs, and/or Paging Occasion, PO, position.-   Embodiment 14: The method according to any one of Embodiments 1-13,    wherein the transmission pattern of the second set of RSs comprises    time and frequency locations, Resource Element (RE) pattern in    symbol(s), period, code sequence, associated Transmission    Configuration Indication (TCI) state of the second set of RSs.-   Embodiment 15: The method according to any one of Embodiments 1-14,    wherein the first set of RSs comprising Synchronization Signal    Blocks, SSBs, and are transmitted periodically, and the second set    of RSs are transmitted in addition to the SSBs to support connected    mode UE operation.-   Embodiment 16: The method according to any one of Embodiments 1-15,    wherein the second set of RSs comprises a Tracking reference symbol,    TRS.-   Embodiment 17: The method according to any one of Embodiments 1-15,    wherein the second set of RSs comprises a Channel State    Information-Reference Signal, CSI-RS.

1. A method performed in a wireless communication device for powersaving when operating in idle mode in a wireless communication system,transmissions of a first set of reference symbols, RSs, and a second setof RSs being provided in the wireless communication system, the methodcomprising: estimating transmission pattern of the second set of RSs bydetecting if the second set of RSs are present during idle mode;determining when to wake up in idle mode to perform associatedmeasurements based on the estimated transmission pattern of the secondset of RSs; and the first set of RSs are provided periodically, and thesecond set of RSs are provided in any of periodic, semi-persistent oraperiodic transmission patterns, the first set of RSs comprisingSynchronization Signal Blocks, SSBs, and the second set of RSs comprisesnon SSBs, the wireless communication device comprising a main receiverand a receiver operating at a lower power than the main receiver, andthe detecting if the second set of RSs are present during idle modecomprises waking up the receiver operating at a lower power than themain receiver of the wireless communication device at an expectedarrival time of the second set of RSs to detect the presence or absenceof the second set of RSs.
 2. The method according to claim 1, furthercomprising receiving information on provision schedule for the secondset of RSs during operation in connected mode from a network node, andwherein the estimating of the transmission pattern of the second set ofRSs is based on the received information.
 3. (canceled)
 4. (canceled) 5.The method according to claim 1, wherein the detecting if the second setof RSs are present during idle mode comprises correlating a receivedsignal sample sequence with a reference sequence corresponding to an RSin the second set of RSs in time or frequency domain to verify whetheran RS is present or not.
 6. The method according to claim 1, wherein thedetecting if the second set of RSs are present during idle modecomprises correlating with several RS sequences, assumed to belong tothe second set, modified based on any one of time offset, frequencyoffset or speed.
 7. The method according to claim 1, wherein thedetecting if the second set of RSs is present during idle mode isperformed one or more times in different cells, bandwidth parts, BWPs,beams, or frequency ranges based on one or more of time and location. 8.The method according to claim 1, wherein the detecting if the second setof RSs is present during idle mode in a present cell is based on thesecond set of RSs' configuration parameters in previous serving cells.9. The method according to claim 1, wherein detecting if the second setof RSs is present during idle mode comprises blind detection.
 10. Themethod according to claim 1, wherein the detecting if the second set ofRSs is present during idle mode is based on energy detection to identifysymbols where the second set of RS s are likely transmitted.
 11. Themethod according to claim 1, wherein detecting if the second set of RSsis present during idle mode is based on correlating energy detections insymbols to decide whether detected energy level or detected energypattern matches an expected RS energy or pattern.
 12. The methodaccording to claim 1, wherein the determining when to wake up to performassociated measurements comprises adjusting one or more of automaticgain control, AGC, automatic frequency control, AFC, time and/or andfrequency synchronization procedures for power savings based on thetransmission pattern of the second set of RSs.
 13. The method accordingto claim 1, wherein the determining when to wake up to performassociated measurements is based on occurrences of the RSs of the firstand the second sets.
 14. The method according to claim 1, wherein thedetermining when to wake up to perform associated measurements comprisesadjusting sleeping in the idle mode based on a temporal order ofoccurrence of the first and second set of RSs.
 15. The method accordingto claim 1, wherein the determining when to wake up to performassociated measurements comprises determining which RS to use for idlemode tasks based on a temporal order of occurrence of the first andsecond set of RSs, and occurrence of a Paging Occasion, PO.
 16. Themethod according to claim 1, wherein the transmission pattern of thesecond set of RSs comprises one or more of time and frequencyallocations, Resource Element, RE, pattern in symbol(s), period, codesequence, associated Transmission Configuration Indication, TCI, stateof the second set of RSs. 17-19. (canceled)
 20. A wireless communicationdevice for a wireless communication, transmissions of a first set ofreference symbols, RSs, and a second set of RSs being provided in thewireless communication system, the wireless communication devicecomprising a a receiver, a transmitter, and a first processor whichcomprise a determiner, and a second processor, to configure the wirelesscommunication device to: estimate transmission pattern of the second setof RSs by detecting if the second set of RSs are present during idlemode; determine when to wake up in idle mode to perform associatedmeasurements based on the estimated transmission pattern of the secondset of RSs; and the first set of RSs are provided periodically, and thesecond set of RSs are provided in any of periodic, semi-persistent oraperiodic transmission patterns, the first set of RSs comprisingSynchronization Signal Blocks, SSBs, and the second set of RSs comprisesnon SSBs, the wireless communication device comprising a main receiverand a receiver operating at a lower power than the main receiver, andthe detecting if the second set of RSs are present during idle modecomprises waking up the receiver operating at a lower power than themain receiver of the wireless communication device at an expectedarrival time of the second set of RSs to detect the presence or absenceof the second set of RSs.
 21. The method according to claim 5, whereinthe detecting if the second set of RSs is present during idle mode isperformed one or more times in different cells, bandwidth parts, BWPs,beams, or frequency ranges based on one or more of time and location.22. The method according to claim 5, wherein the detecting if the secondset of RSs is present during idle mode in a present cell is based on thesecond set of RSs' configuration parameters in previous serving cells.23. The method according to claim 5, wherein detecting if the second setof RSs is present during idle mode comprises blind detection.
 24. Themethod according to claim 5, wherein the detecting if the second set ofRSs is present during idle mode is based on energy detection to identifysymbols where the second set of RSs are likely transmitted.
 25. Themethod according to claim 5, wherein detecting if the second set of RSsis present during idle mode is based on correlating energy detections insymbols to decide whether detected energy level or detected energypattern matches an expected RS energy or pattern.